Lingual thyroid. A case report

We describe an unusual clinical case in which a non functional cervical thyroid coexisted with a functional ectopic lingual thyroid. A twenty-year-old woman was referred for hypothyroidism treated with L-thyroxin related to a basilingual tumor diagnosed 8 years previously. Oropharyngeal examination showed a spherical basilingual tumor 2.5 cm in diameter. Laboratory findings during treatment with 50 microgram of L-thyroxin daily showed: TSH 6,280 microIU/ml (N: 4,4 to 3.6), FT3 4,2 pmol/l (N: 3.3 to 5.1), and FT4 15.4 pmol/l (N: 10,5 to 25,5). Antithyroid antibodies were absent. Cervical ultrasonography showed a small hypoechogenic, heterogeneous orthotopic thyroid gland confirmed by cervical computed tomography thyroid. An I(123) scan revealed uptake above the chin on the profile, and no significant uptake is the area of the normal thyroid. The lack of iodine uptake by the cervical thyroid remains unexplained. In conclusion, this report of an ectopic thyroid location in unusual because of the coexistence of non functional cervical thyroid and of a partially functional lingual thyroid tissue. The pathogenesis of this association remains unclear.